Revenue comes from selling ads, giving revenue away for no returns simply to get everyone to join is nonsense and let's sat that eventually everyone joins Facebook

Take Instagram for example? The model for Instagram isn't simply to sell ads. Instagram is about influence and influencers. It's about the attention economy. There is a scarce amount of human attention in the market. In order for there to be accounts with millions of followers there has to be a way for those accounts to get attention.

Right there you have all the market dynamics necessary to make plenty of money without having to use traditional ad models. What you're talking about is traditional revenue generating business models. Instagram isn't the traditional model and neither is Facebook or Amazon.

I admit you can make a case that currently the Facebook like economy which is a market of it's own, is currently not using a currency which people are valuing in USD. While Steem has the same upvote economy which is using a currency people value in USD.

If Facebook has a stable token and it's more stable than the Steem Dollar this changes things. Suddenly Facebook at any time could decide to integrate this token into Instagram, Facebook, or WhatsApp. This token alone would potentially kill Steem depending on how Facebook chooses to integrate it.

Facebook could choose to for example pay the user to watch ads or interact with certain accounts. The money would come from accounts which want more attention from users. Facebook could take a small cut of the profit, say 20%, and the 80% goes to the users. So there is no reason to believe Facebook would somehow lose money.

We see the model already on Coinbase with Coinbase Earn. When you watch a video and answer some quiz questions you earn tokens. This model scales, and Instagram could integrate it.